crates/ide_completion/src/context.rs

   1 //! See `CompletionContext` structure.
   2
   3 use base_db::SourceDatabaseExt;
   4 use hir::{Local, Name, ScopeDef, Semantics, SemanticsScope, Type, TypeInfo};
   5 use ide_db::{
   6     base_db::{FilePosition, SourceDatabase},
   7     call_info::ActiveParameter,
   8     RootDatabase,
   9 };
  10 use syntax::{
  11     algo::find_node_at_offset,
  12     ast::{self, NameOrNameRef, NameOwner},
  13     match_ast, AstNode, NodeOrToken,
  14     SyntaxKind::{self, *},
  15     SyntaxNode, SyntaxToken, TextRange, TextSize, T,
  16 };
  17 use text_edit::Indel;
  18
  19 use crate::{
  20     patterns::{
  21         determine_location, determine_prev_sibling, for_is_prev2, inside_impl_trait_block,
  22         is_in_loop_body, previous_token, ImmediateLocation, ImmediatePrevSibling,
  23     },
  24     CompletionConfig,
  25 };
  26
  27 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  28 pub(crate) enum PatternRefutability {
  29     Refutable,
  30     Irrefutable,
  31 }
  32
  33 #[derive(Debug)]
  34 pub(super) enum PathKind {
  35     Expr,
  36     Type,
  37 }
  38
  39 #[derive(Debug)]
  40 pub(crate) struct PathCompletionContext {
  41     /// If this is a call with () already there
  42     call_kind: Option<CallKind>,
  43     /// A single-indent path, like `foo`. `::foo` should not be considered a trivial path.
  44     pub(super) is_trivial_path: bool,
  45     /// If not a trivial path, the prefix (qualifier).
  46     pub(super) qualifier: Option<ast::Path>,
  47     /// Whether the qualifier comes from a use tree parent or not
  48     pub(super) use_tree_parent: bool,
  49     pub(super) kind: Option<PathKind>,
  50     /// Whether the path segment has type args or not.
  51     pub(super) has_type_args: bool,
  52     /// `true` if we are a statement or a last expr in the block.
  53     pub(super) can_be_stmt: bool,
  54     pub(super) in_loop_body: bool,
  55 }
  56
  57 #[derive(Debug)]
  58 pub(super) struct PatternContext {
  59     pub(super) refutability: PatternRefutability,
  60     pub(super) is_param: Option<ParamKind>,
  61 }
  62
  63 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  64 pub(crate) enum CallKind {
  65     Pat,
  66     Mac,
  67     Expr,
  68 }
  69
  70 #[derive(Copy, Clone, Debug, PartialEq, Eq)]
  71 pub(crate) enum ParamKind {
  72     Function,
  73     Closure,
  74 }
  75 /// `CompletionContext` is created early during completion to figure out, where
  76 /// exactly is the cursor, syntax-wise.
  77 #[derive(Debug)]
  78 pub(crate) struct CompletionContext<'a> {
  79     pub(super) sema: Semantics<'a, RootDatabase>,
  80     pub(super) scope: SemanticsScope<'a>,
  81     pub(super) db: &'a RootDatabase,
  82     pub(super) config: &'a CompletionConfig,
  83     pub(super) position: FilePosition,
  84     /// The token before the cursor, in the original file.
  85     pub(super) original_token: SyntaxToken,
  86     /// The token before the cursor, in the macro-expanded file.
  87     pub(super) token: SyntaxToken,
  88     pub(super) krate: Option<hir::Crate>,
  89     pub(super) expected_name: Option<NameOrNameRef>,
  90     pub(super) expected_type: Option<Type>,
  91
  92     /// The parent function of the cursor position if it exists.
  93     pub(super) function_def: Option<ast::Fn>,
  94     /// The parent impl of the cursor position if it exists.
  95     pub(super) impl_def: Option<ast::Impl>,
  96     pub(super) name_ref_syntax: Option<ast::NameRef>,
  97
  98     // potentially set if we are completing a lifetime
  99     pub(super) lifetime_syntax: Option<ast::Lifetime>,
 100     pub(super) lifetime_param_syntax: Option<ast::LifetimeParam>,
 101     pub(super) lifetime_allowed: bool,
 102     pub(super) is_label_ref: bool,
 103
 104     pub(super) completion_location: Option<ImmediateLocation>,
 105     pub(super) prev_sibling: Option<ImmediatePrevSibling>,
 106     pub(super) attribute_under_caret: Option<ast::Attr>,
 107     pub(super) previous_token: Option<SyntaxToken>,
 108
 109     pub(super) pattern_ctx: Option<PatternContext>,
 110     pub(super) path_context: Option<PathCompletionContext>,
 111     pub(super) active_parameter: Option<ActiveParameter>,
 112     pub(super) locals: Vec<(String, Local)>,
 113
 114     pub(super) incomplete_let: bool,
 115
 116     no_completion_required: bool,
 117 }
 118
 119 impl<'a> CompletionContext<'a> {
 120     pub(super) fn new(
 121         db: &'a RootDatabase,
 122         position: FilePosition,
 123         config: &'a CompletionConfig,
 124     ) -> Option<CompletionContext<'a>> {
 125         let sema = Semantics::new(db);
 126
 127         let original_file = sema.parse(position.file_id);
 128
 129         // Insert a fake ident to get a valid parse tree. We will use this file
 130         // to determine context, though the original_file will be used for
 131         // actual completion.
 132         let file_with_fake_ident = {
 133             let parse = db.parse(position.file_id);
 134             let edit = Indel::insert(position.offset, "intellijRulezz".to_string());
 135             parse.reparse(&edit).tree()
 136         };
 137         let fake_ident_token =
 138             file_with_fake_ident.syntax().token_at_offset(position.offset).right_biased().unwrap();
 139
 140         let krate = sema.to_module_def(position.file_id).map(|m| m.krate());
 141         let original_token =
 142             original_file.syntax().token_at_offset(position.offset).left_biased()?;
 143         let token = sema.descend_into_macros(original_token.clone());
 144         let scope = sema.scope_at_offset(&token, position.offset);
 145         let mut locals = vec![];
 146         scope.process_all_names(&mut |name, scope| {
 147             if let ScopeDef::Local(local) = scope {
 148                 locals.push((name.to_string(), local));
 149             }
 150         });
 151         let mut ctx = CompletionContext {
 152             sema,
 153             scope,
 154             db,
 155             config,
 156             position,
 157             original_token,
 158             token,
 159             krate,
 160             expected_name: None,
 161             expected_type: None,
 162             function_def: None,
 163             impl_def: None,
 164             name_ref_syntax: None,
 165             lifetime_syntax: None,
 166             lifetime_param_syntax: None,
 167             lifetime_allowed: false,
 168             is_label_ref: false,
 169             pattern_ctx: None,
 170             completion_location: None,
 171             prev_sibling: None,
 172             attribute_under_caret: None,
 173             previous_token: None,
 174             path_context: None,
 175             active_parameter: ActiveParameter::at(db, position),
 176             locals,
 177             incomplete_let: false,
 178             no_completion_required: false,
 179         };
 180
 181         let mut original_file = original_file.syntax().clone();
 182         let mut speculative_file = file_with_fake_ident.syntax().clone();
 183         let mut offset = position.offset;
 184         let mut fake_ident_token = fake_ident_token;
 185
 186         // Are we inside a macro call?
 187         while let (Some(actual_macro_call), Some(macro_call_with_fake_ident)) = (
 188             find_node_at_offset::<ast::MacroCall>(&original_file, offset),
 189             find_node_at_offset::<ast::MacroCall>(&speculative_file, offset),
 190         ) {
 191             if actual_macro_call.path().as_ref().map(|s| s.syntax().text())
 192                 != macro_call_with_fake_ident.path().as_ref().map(|s| s.syntax().text())
 193             {
 194                 break;
 195             }
 196             let speculative_args = match macro_call_with_fake_ident.token_tree() {
 197                 Some(tt) => tt,
 198                 None => break,
 199             };
 200             if let (Some(actual_expansion), Some(speculative_expansion)) = (
 201                 ctx.sema.expand(&actual_macro_call),
 202                 ctx.sema.speculative_expand(
 203                     &actual_macro_call,
 204                     &speculative_args,
 205                     fake_ident_token,
 206                 ),
 207             ) {
 208                 let new_offset = speculative_expansion.1.text_range().start();
 209                 if new_offset > actual_expansion.text_range().end() {
 210                     break;
 211                 }
 212                 original_file = actual_expansion;
 213                 speculative_file = speculative_expansion.0;
 214                 fake_ident_token = speculative_expansion.1;
 215                 offset = new_offset;
 216             } else {
 217                 break;
 218             }
 219         }
 220         ctx.fill(&original_file, speculative_file, offset);
 221         Some(ctx)
 222     }
 223
 224     /// Checks whether completions in that particular case don't make much sense.
 225     /// Examples:
 226     /// - `fn $0` -- we expect function name, it's unlikely that "hint" will be helpful.
 227     ///   Exception for this case is `impl Trait for Foo`, where we would like to hint trait method names.
 228     /// - `for _ i$0` -- obviously, it'll be "in" keyword.
 229     pub(crate) fn no_completion_required(&self) -> bool {
 230         self.no_completion_required
 231     }
 232
 233     /// The range of the identifier that is being completed.
 234     pub(crate) fn source_range(&self) -> TextRange {
 235         // check kind of macro-expanded token, but use range of original token
 236         let kind = self.token.kind();
 237         if kind == IDENT || kind == LIFETIME_IDENT || kind == UNDERSCORE || kind.is_keyword() {
 238             cov_mark::hit!(completes_if_prefix_is_keyword);
 239             self.original_token.text_range()
 240         } else if kind == CHAR {
 241             // assume we are completing a lifetime but the user has only typed the '
 242             cov_mark::hit!(completes_if_lifetime_without_idents);
 243             TextRange::at(self.original_token.text_range().start(), TextSize::from(1))
 244         } else {
 245             TextRange::empty(self.position.offset)
 246         }
 247     }
 248
 249     pub(crate) fn previous_token_is(&self, kind: SyntaxKind) -> bool {
 250         self.previous_token.as_ref().map_or(false, |tok| tok.kind() == kind)
 251     }
 252
 253     pub(crate) fn expects_assoc_item(&self) -> bool {
 254         matches!(self.completion_location, Some(ImmediateLocation::Trait | ImmediateLocation::Impl))
 255     }
 256
 257     pub(crate) fn has_dot_receiver(&self) -> bool {
 258         matches!(
 259             &self.completion_location,
 260             Some(ImmediateLocation::FieldAccess { receiver, .. } | ImmediateLocation::MethodCall { receiver,.. })
 261                 if receiver.is_some()
 262         )
 263     }
 264
 265     pub(crate) fn dot_receiver(&self) -> Option<&ast::Expr> {
 266         match &self.completion_location {
 267             Some(
 268                 ImmediateLocation::MethodCall { receiver, .. }
 269                 | ImmediateLocation::FieldAccess { receiver, .. },
 270             ) => receiver.as_ref(),
 271             _ => None,
 272         }
 273     }
 274
 275     pub(crate) fn expects_non_trait_assoc_item(&self) -> bool {
 276         matches!(self.completion_location, Some(ImmediateLocation::Impl))
 277     }
 278
 279     pub(crate) fn expects_item(&self) -> bool {
 280         matches!(self.completion_location, Some(ImmediateLocation::ItemList))
 281     }
 282
 283     pub(crate) fn expects_generic_arg(&self) -> bool {
 284         matches!(self.completion_location, Some(ImmediateLocation::GenericArgList(_)))
 285     }
 286
 287     pub(crate) fn has_block_expr_parent(&self) -> bool {
 288         matches!(self.completion_location, Some(ImmediateLocation::BlockExpr))
 289     }
 290
 291     pub(crate) fn expects_ident_pat_or_ref_expr(&self) -> bool {
 292         matches!(
 293             self.completion_location,
 294             Some(ImmediateLocation::IdentPat | ImmediateLocation::RefExpr)
 295         )
 296     }
 297
 298     pub(crate) fn expect_field(&self) -> bool {
 299         matches!(
 300             self.completion_location,
 301             Some(ImmediateLocation::RecordField | ImmediateLocation::TupleField)
 302         )
 303     }
 304
 305     pub(crate) fn in_use_tree(&self) -> bool {
 306         matches!(
 307             self.completion_location,
 308             Some(ImmediateLocation::Use | ImmediateLocation::UseTree)
 309         )
 310     }
 311
 312     pub(crate) fn has_impl_or_trait_prev_sibling(&self) -> bool {
 313         matches!(
 314             self.prev_sibling,
 315             Some(ImmediatePrevSibling::ImplDefType | ImmediatePrevSibling::TraitDefName)
 316         )
 317     }
 318
 319     pub(crate) fn has_impl_prev_sibling(&self) -> bool {
 320         matches!(self.prev_sibling, Some(ImmediatePrevSibling::ImplDefType))
 321     }
 322
 323     pub(crate) fn has_visibility_prev_sibling(&self) -> bool {
 324         matches!(self.prev_sibling, Some(ImmediatePrevSibling::Visibility))
 325     }
 326
 327     pub(crate) fn after_if(&self) -> bool {
 328         matches!(self.prev_sibling, Some(ImmediatePrevSibling::IfExpr))
 329     }
 330
 331     pub(crate) fn is_path_disallowed(&self) -> bool {
 332         self.attribute_under_caret.is_some()
 333             || self.previous_token_is(T![unsafe])
 334             || matches!(
 335                 self.prev_sibling,
 336                 Some(ImmediatePrevSibling::Attribute | ImmediatePrevSibling::Visibility)
 337             )
 338             || matches!(
 339                 self.completion_location,
 340                 Some(
 341                     ImmediateLocation::Attribute(_)
 342                         | ImmediateLocation::ModDeclaration(_)
 343                         | ImmediateLocation::RecordPat(_)
 344                         | ImmediateLocation::RecordExpr(_)
 345                 )
 346             )
 347     }
 348
 349     pub(crate) fn expects_expression(&self) -> bool {
 350         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Expr), .. }))
 351     }
 352
 353     pub(crate) fn expects_type(&self) -> bool {
 354         matches!(self.path_context, Some(PathCompletionContext { kind: Some(PathKind::Type), .. }))
 355     }
 356
 357     pub(crate) fn path_call_kind(&self) -> Option<CallKind> {
 358         self.path_context.as_ref().and_then(|it| it.call_kind)
 359     }
 360
 361     pub(crate) fn is_trivial_path(&self) -> bool {
 362         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: true, .. }))
 363     }
 364
 365     pub(crate) fn is_non_trivial_path(&self) -> bool {
 366         matches!(self.path_context, Some(PathCompletionContext { is_trivial_path: false, .. }))
 367     }
 368
 369     pub(crate) fn path_qual(&self) -> Option<&ast::Path> {
 370         self.path_context.as_ref().and_then(|it| it.qualifier.as_ref())
 371     }
 372
 373     /// Checks if an item is visible and not `doc(hidden)` at the completion site.
 374     pub(crate) fn is_visible<I>(&self, item: &I) -> bool
 375     where
 376         I: hir::HasVisibility + hir::HasAttrs + hir::HasCrate + Copy,
 377     {
 378         self.is_visible_impl(&item.visibility(self.db), &item.attrs(self.db), item.krate(self.db))
 379     }
 380
 381     pub(crate) fn is_scope_def_hidden(&self, scope_def: &ScopeDef) -> bool {
 382         if let (Some(attrs), Some(krate)) = (scope_def.attrs(self.db), scope_def.krate(self.db)) {
 383             return self.is_doc_hidden(&attrs, krate);
 384         }
 385
 386         false
 387     }
 388
 389     pub(crate) fn is_item_hidden(&self, item: &hir::ItemInNs) -> bool {
 390         let attrs = item.attrs(self.db);
 391         let krate = item.krate(self.db);
 392         match (attrs, krate) {
 393             (Some(attrs), Some(krate)) => self.is_doc_hidden(&attrs, krate),
 394             _ => false,
 395         }
 396     }
 397
 398     /// A version of [`SemanticsScope::process_all_names`] that filters out `#[doc(hidden)]` items.
 399     pub(crate) fn process_all_names(&self, f: &mut dyn FnMut(Name, ScopeDef)) {
 400         self.scope.process_all_names(&mut |name, def| {
 401             if self.is_scope_def_hidden(&def) {
 402                 return;
 403             }
 404
 405             f(name, def);
 406         })
 407     }
 408
 409     fn is_visible_impl(
 410         &self,
 411         vis: &hir::Visibility,
 412         attrs: &hir::Attrs,
 413         defining_crate: hir::Crate,
 414     ) -> bool {
 415         let module = match self.scope.module() {
 416             Some(it) => it,
 417             None => return false,
 418         };
 419         if !vis.is_visible_from(self.db, module.into()) {
 420             // If the definition location is editable, also show private items
 421             let root_file = defining_crate.root_file(self.db);
 422             let source_root_id = self.db.file_source_root(root_file);
 423             let is_editable = !self.db.source_root(source_root_id).is_library;
 424             return is_editable;
 425         }
 426
 427         !self.is_doc_hidden(attrs, defining_crate)
 428     }
 429
 430     fn is_doc_hidden(&self, attrs: &hir::Attrs, defining_crate: hir::Crate) -> bool {
 431         let module = match self.scope.module() {
 432             Some(it) => it,
 433             None => return true,
 434         };
 435         if module.krate() != defining_crate && attrs.has_doc_hidden() {
 436             // `doc(hidden)` items are only completed within the defining crate.
 437             return true;
 438         }
 439
 440         false
 441     }
 442
 443     fn fill_impl_def(&mut self) {
 444         self.impl_def = self
 445             .sema
 446             .token_ancestors_with_macros(self.token.clone())
 447             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 448             .find_map(ast::Impl::cast);
 449     }
 450
 451     fn expected_type_and_name(&self) -> (Option<Type>, Option<NameOrNameRef>) {
 452         let mut node = match self.token.parent() {
 453             Some(it) => it,
 454             None => return (None, None),
 455         };
 456         loop {
 457             break match_ast! {
 458                 match node {
 459                     ast::LetStmt(it) => {
 460                         cov_mark::hit!(expected_type_let_with_leading_char);
 461                         cov_mark::hit!(expected_type_let_without_leading_char);
 462                         let ty = it.pat()
 463                             .and_then(|pat| self.sema.type_of_pat(&pat))
 464                             .or_else(|| it.initializer().and_then(|it| self.sema.type_of_expr(&it)))
 465                             .map(TypeInfo::original);
 466                         let name = if let Some(ast::Pat::IdentPat(ident)) = it.pat() {
 467                             ident.name().map(NameOrNameRef::Name)
 468                         } else {
 469                             None
 470                         };
 471
 472                         (ty, name)
 473                     },
 474                     ast::ArgList(_it) => {
 475                         cov_mark::hit!(expected_type_fn_param);
 476                         ActiveParameter::at_token(
 477                             &self.sema,
 478                             self.token.clone(),
 479                         ).map(|ap| {
 480                             let name = ap.ident().map(NameOrNameRef::Name);
 481                             let ty = if has_ref(&self.token) {
 482                                 cov_mark::hit!(expected_type_fn_param_ref);
 483                                 ap.ty.remove_ref()
 484                             } else {
 485                                 Some(ap.ty)
 486                             };
 487                             (ty, name)
 488                         })
 489                         .unwrap_or((None, None))
 490                     },
 491                     ast::RecordExprFieldList(it) => {
 492                         // wouldn't try {} be nice...
 493                         (|| {
 494                             if self.token.kind() == T![..]
 495                                 || self.token.prev_token().map(|t| t.kind()) == Some(T![..])
 496                             {
 497                                 cov_mark::hit!(expected_type_struct_func_update);
 498                                 let record_expr = it.syntax().parent().and_then(ast::RecordExpr::cast)?;
 499                                 let ty = self.sema.type_of_expr(&record_expr.into())?;
 500                                 Some((
 501                                     Some(ty.original),
 502                                     None
 503                                 ))
 504                             } else {
 505                                 cov_mark::hit!(expected_type_struct_field_without_leading_char);
 506                                 let expr_field = self.token.prev_sibling_or_token()?
 507                                     .into_node()
 508                                     .and_then(ast::RecordExprField::cast)?;
 509                                 let (_, _, ty) = self.sema.resolve_record_field(&expr_field)?;
 510                                 Some((
 511                                     Some(ty),
 512                                     expr_field.field_name().map(NameOrNameRef::NameRef),
 513                                 ))
 514                             }
 515                         })().unwrap_or((None, None))
 516                     },
 517                     ast::RecordExprField(it) => {
 518                         cov_mark::hit!(expected_type_struct_field_with_leading_char);
 519                         (
 520                             it.expr().as_ref().and_then(|e| self.sema.type_of_expr(e)).map(TypeInfo::original),
 521                             it.field_name().map(NameOrNameRef::NameRef),
 522                         )
 523                     },
 524                     ast::MatchExpr(it) => {
 525                         cov_mark::hit!(expected_type_match_arm_without_leading_char);
 526                         let ty = it.expr().and_then(|e| self.sema.type_of_expr(&e)).map(TypeInfo::original);
 527                         (ty, None)
 528                     },
 529                     ast::IfExpr(it) => {
 530                         cov_mark::hit!(expected_type_if_let_without_leading_char);
 531                         let ty = it.condition()
 532                             .and_then(|cond| cond.expr())
 533                             .and_then(|e| self.sema.type_of_expr(&e))
 534                             .map(TypeInfo::original);
 535                         (ty, None)
 536                     },
 537                     ast::IdentPat(it) => {
 538                         cov_mark::hit!(expected_type_if_let_with_leading_char);
 539                         cov_mark::hit!(expected_type_match_arm_with_leading_char);
 540                         let ty = self.sema.type_of_pat(&ast::Pat::from(it)).map(TypeInfo::original);
 541                         (ty, None)
 542                     },
 543                     ast::Fn(it) => {
 544                         cov_mark::hit!(expected_type_fn_ret_with_leading_char);
 545                         cov_mark::hit!(expected_type_fn_ret_without_leading_char);
 546                         let def = self.sema.to_def(&it);
 547                         (def.map(|def| def.ret_type(self.db)), None)
 548                     },
 549                     ast::ClosureExpr(it) => {
 550                         let ty = self.sema.type_of_expr(&it.into());
 551                         ty.and_then(|ty| ty.original.as_callable(self.db))
 552                             .map(|c| (Some(c.return_type()), None))
 553                             .unwrap_or((None, None))
 554                     },
 555                     ast::Stmt(_it) => (None, None),
 556                     ast::Item(__) => (None, None),
 557                     _ => {
 558                         match node.parent() {
 559                             Some(n) => {
 560                                 node = n;
 561                                 continue;
 562                             },
 563                             None => (None, None),
 564                         }
 565                     },
 566                 }
 567             };
 568         }
 569     }
 570
 571     fn fill(
 572         &mut self,
 573         original_file: &SyntaxNode,
 574         file_with_fake_ident: SyntaxNode,
 575         offset: TextSize,
 576     ) {
 577         let fake_ident_token = file_with_fake_ident.token_at_offset(offset).right_biased().unwrap();
 578         let syntax_element = NodeOrToken::Token(fake_ident_token);
 579         self.previous_token = previous_token(syntax_element.clone());
 580         self.attribute_under_caret = syntax_element.ancestors().find_map(ast::Attr::cast);
 581         self.no_completion_required = {
 582             let inside_impl_trait_block = inside_impl_trait_block(syntax_element.clone());
 583             let fn_is_prev = self.previous_token_is(T![fn]);
 584             let for_is_prev2 = for_is_prev2(syntax_element.clone());
 585             (fn_is_prev && !inside_impl_trait_block) || for_is_prev2
 586         };
 587
 588         self.incomplete_let =
 589             syntax_element.ancestors().take(6).find_map(ast::LetStmt::cast).map_or(false, |it| {
 590                 it.syntax().text_range().end() == syntax_element.text_range().end()
 591             });
 592
 593         let (expected_type, expected_name) = self.expected_type_and_name();
 594         self.expected_type = expected_type;
 595         self.expected_name = expected_name;
 596
 597         let name_like = match find_node_at_offset(&file_with_fake_ident, offset) {
 598             Some(it) => it,
 599             None => return,
 600         };
 601         self.completion_location =
 602             determine_location(&self.sema, original_file, offset, &name_like);
 603         self.prev_sibling = determine_prev_sibling(&name_like);
 604         match name_like {
 605             ast::NameLike::Lifetime(lifetime) => {
 606                 self.classify_lifetime(original_file, lifetime, offset);
 607             }
 608             ast::NameLike::NameRef(name_ref) => {
 609                 self.classify_name_ref(original_file, name_ref);
 610             }
 611             ast::NameLike::Name(name) => {
 612                 self.classify_name(name);
 613             }
 614         }
 615     }
 616
 617     fn classify_lifetime(
 618         &mut self,
 619         original_file: &SyntaxNode,
 620         lifetime: ast::Lifetime,
 621         offset: TextSize,
 622     ) {
 623         self.lifetime_syntax =
 624             find_node_at_offset(original_file, lifetime.syntax().text_range().start());
 625         if let Some(parent) = lifetime.syntax().parent() {
 626             if parent.kind() == ERROR {
 627                 return;
 628             }
 629
 630             match_ast! {
 631                 match parent {
 632                     ast::LifetimeParam(_it) => {
 633                         self.lifetime_allowed = true;
 634                         self.lifetime_param_syntax =
 635                             self.sema.find_node_at_offset_with_macros(original_file, offset);
 636                     },
 637                     ast::BreakExpr(_it) => self.is_label_ref = true,
 638                     ast::ContinueExpr(_it) => self.is_label_ref = true,
 639                     ast::Label(_it) => (),
 640                     _ => self.lifetime_allowed = true,
 641                 }
 642             }
 643         }
 644     }
 645
 646     fn classify_name(&mut self, name: ast::Name) {
 647         self.fill_impl_def();
 648
 649         if let Some(bind_pat) = name.syntax().parent().and_then(ast::IdentPat::cast) {
 650             let is_name_in_field_pat = bind_pat
 651                 .syntax()
 652                 .parent()
 653                 .and_then(ast::RecordPatField::cast)
 654                 .map_or(false, |pat_field| pat_field.name_ref().is_none());
 655             if is_name_in_field_pat {
 656                 return;
 657             }
 658             if bind_pat.is_simple_ident() {
 659                 let mut is_param = None;
 660                 let refutability = bind_pat
 661                     .syntax()
 662                     .ancestors()
 663                     .skip_while(|it| ast::Pat::can_cast(it.kind()))
 664                     .next()
 665                     .map_or(PatternRefutability::Irrefutable, |node| {
 666                         match_ast! {
 667                             match node {
 668                                 ast::LetStmt(__) => PatternRefutability::Irrefutable,
 669                                 ast::Param(param) => {
 670                                     let is_closure_param = param
 671                                         .syntax()
 672                                         .ancestors()
 673                                         .nth(2)
 674                                         .and_then(ast::ClosureExpr::cast)
 675                                         .is_some();
 676                                     is_param = Some(if is_closure_param {
 677                                         ParamKind::Closure
 678                                     } else {
 679                                         ParamKind::Function
 680                                     });
 681                                     PatternRefutability::Irrefutable
 682                                 },
 683                                 ast::MatchArm(__) => PatternRefutability::Refutable,
 684                                 ast::Condition(__) => PatternRefutability::Refutable,
 685                                 ast::ForExpr(__) => PatternRefutability::Irrefutable,
 686                                 _ => PatternRefutability::Irrefutable,
 687                             }
 688                         }
 689                     });
 690                 self.pattern_ctx = Some(PatternContext { refutability, is_param });
 691             }
 692         }
 693     }
 694
 695     fn classify_name_ref(&mut self, original_file: &SyntaxNode, name_ref: ast::NameRef) {
 696         self.fill_impl_def();
 697
 698         self.name_ref_syntax =
 699             find_node_at_offset(original_file, name_ref.syntax().text_range().start());
 700
 701         self.function_def = self
 702             .sema
 703             .token_ancestors_with_macros(self.token.clone())
 704             .take_while(|it| it.kind() != SOURCE_FILE && it.kind() != MODULE)
 705             .find_map(ast::Fn::cast);
 706
 707         let parent = match name_ref.syntax().parent() {
 708             Some(it) => it,
 709             None => return,
 710         };
 711
 712         if let Some(segment) = ast::PathSegment::cast(parent) {
 713             let path_ctx = self.path_context.get_or_insert(PathCompletionContext {
 714                 call_kind: None,
 715                 is_trivial_path: false,
 716                 qualifier: None,
 717                 has_type_args: false,
 718                 can_be_stmt: false,
 719                 in_loop_body: false,
 720                 use_tree_parent: false,
 721                 kind: None,
 722             });
 723             path_ctx.in_loop_body = is_in_loop_body(name_ref.syntax());
 724             let path = segment.parent_path();
 725
 726             if let Some(p) = path.syntax().parent() {
 727                 path_ctx.call_kind = match_ast! {
 728                     match p {
 729                         ast::PathExpr(it) => it.syntax().parent().and_then(ast::CallExpr::cast).map(|_| CallKind::Expr),
 730                         ast::MacroCall(it) => it.excl_token().and(Some(CallKind::Mac)),
 731                         ast::TupleStructPat(_it) => Some(CallKind::Pat),
 732                         _ => None
 733                     }
 734                 };
 735             }
 736
 737             if let Some(parent) = path.syntax().parent() {
 738                 path_ctx.kind = match_ast! {
 739                     match parent {
 740                         ast::PathType(_it) => Some(PathKind::Type),
 741                         ast::PathExpr(_it) => Some(PathKind::Expr),
 742                         _ => None,
 743                     }
 744                 };
 745             }
 746             path_ctx.has_type_args = segment.generic_arg_list().is_some();
 747
 748             if let Some((path, use_tree_parent)) = path_or_use_tree_qualifier(&path) {
 749                 path_ctx.use_tree_parent = use_tree_parent;
 750                 path_ctx.qualifier = path
 751                     .segment()
 752                     .and_then(|it| {
 753                         find_node_with_range::<ast::PathSegment>(
 754                             original_file,
 755                             it.syntax().text_range(),
 756                         )
 757                     })
 758                     .map(|it| it.parent_path());
 759                 return;
 760             }
 761
 762             if let Some(segment) = path.segment() {
 763                 if segment.coloncolon_token().is_some() {
 764                     return;
 765                 }
 766             }
 767
 768             path_ctx.is_trivial_path = true;
 769
 770             // Find either enclosing expr statement (thing with `;`) or a
 771             // block. If block, check that we are the last expr.
 772             path_ctx.can_be_stmt = name_ref
 773                 .syntax()
 774                 .ancestors()
 775                 .find_map(|node| {
 776                     if let Some(stmt) = ast::ExprStmt::cast(node.clone()) {
 777                         return Some(stmt.syntax().text_range() == name_ref.syntax().text_range());
 778                     }
 779                     if let Some(block) = ast::BlockExpr::cast(node) {
 780                         return Some(
 781                             block.tail_expr().map(|e| e.syntax().text_range())
 782                                 == Some(name_ref.syntax().text_range()),
 783                         );
 784                     }
 785                     None
 786                 })
 787                 .unwrap_or(false);
 788         }
 789     }
 790 }
 791
 792 fn find_node_with_range<N: AstNode>(syntax: &SyntaxNode, range: TextRange) -> Option<N> {
 793     syntax.covering_element(range).ancestors().find_map(N::cast)
 794 }
 795
 796 fn path_or_use_tree_qualifier(path: &ast::Path) -> Option<(ast::Path, bool)> {
 797     if let Some(qual) = path.qualifier() {
 798         return Some((qual, false));
 799     }
 800     let use_tree_list = path.syntax().ancestors().find_map(ast::UseTreeList::cast)?;
 801     let use_tree = use_tree_list.syntax().parent().and_then(ast::UseTree::cast)?;
 802     use_tree.path().zip(Some(true))
 803 }
 804
 805 fn has_ref(token: &SyntaxToken) -> bool {
 806     let mut token = token.clone();
 807     for skip in [WHITESPACE, IDENT, T![mut]] {
 808         if token.kind() == skip {
 809             token = match token.prev_token() {
 810                 Some(it) => it,
 811                 None => return false,
 812             }
 813         }
 814     }
 815     token.kind() == T![&]
 816 }
 817
 818 #[cfg(test)]
 819 mod tests {
 820     use expect_test::{expect, Expect};
 821     use hir::HirDisplay;
 822
 823     use crate::tests::{position, TEST_CONFIG};
 824
 825     use super::CompletionContext;
 826
 827     fn check_expected_type_and_name(ra_fixture: &str, expect: Expect) {
 828         let (db, pos) = position(ra_fixture);
 829         let completion_context = CompletionContext::new(&db, pos, &TEST_CONFIG).unwrap();
 830
 831         let ty = completion_context
 832             .expected_type
 833             .map(|t| t.display_test(&db).to_string())
 834             .unwrap_or("?".to_owned());
 835
 836         let name = completion_context
 837             .expected_name
 838             .map_or_else(|| "?".to_owned(), |name| name.to_string());
 839
 840         expect.assert_eq(&format!("ty: {}, name: {}", ty, name));
 841     }
 842
 843     #[test]
 844     fn expected_type_let_without_leading_char() {
 845         cov_mark::check!(expected_type_let_without_leading_char);
 846         check_expected_type_and_name(
 847             r#"
 848 fn foo() {
 849     let x: u32 = $0;
 850 }
 851 "#,
 852             expect![[r#"ty: u32, name: x"#]],
 853         );
 854     }
 855
 856     #[test]
 857     fn expected_type_let_with_leading_char() {
 858         cov_mark::check!(expected_type_let_with_leading_char);
 859         check_expected_type_and_name(
 860             r#"
 861 fn foo() {
 862     let x: u32 = c$0;
 863 }
 864 "#,
 865             expect![[r#"ty: u32, name: x"#]],
 866         );
 867     }
 868
 869     #[test]
 870     fn expected_type_let_pat() {
 871         check_expected_type_and_name(
 872             r#"
 873 fn foo() {
 874     let x$0 = 0u32;
 875 }
 876 "#,
 877             expect![[r#"ty: u32, name: ?"#]],
 878         );
 879         check_expected_type_and_name(
 880             r#"
 881 fn foo() {
 882     let $0 = 0u32;
 883 }
 884 "#,
 885             expect![[r#"ty: u32, name: ?"#]],
 886         );
 887     }
 888
 889     #[test]
 890     fn expected_type_fn_param() {
 891         cov_mark::check!(expected_type_fn_param);
 892         check_expected_type_and_name(
 893             r#"
 894 fn foo() { bar($0); }
 895 fn bar(x: u32) {}
 896 "#,
 897             expect![[r#"ty: u32, name: x"#]],
 898         );
 899         check_expected_type_and_name(
 900             r#"
 901 fn foo() { bar(c$0); }
 902 fn bar(x: u32) {}
 903 "#,
 904             expect![[r#"ty: u32, name: x"#]],
 905         );
 906     }
 907
 908     #[test]
 909     fn expected_type_fn_param_ref() {
 910         cov_mark::check!(expected_type_fn_param_ref);
 911         check_expected_type_and_name(
 912             r#"
 913 fn foo() { bar(&$0); }
 914 fn bar(x: &u32) {}
 915 "#,
 916             expect![[r#"ty: u32, name: x"#]],
 917         );
 918         check_expected_type_and_name(
 919             r#"
 920 fn foo() { bar(&mut $0); }
 921 fn bar(x: &mut u32) {}
 922 "#,
 923             expect![[r#"ty: u32, name: x"#]],
 924         );
 925         check_expected_type_and_name(
 926             r#"
 927 fn foo() { bar(&c$0); }
 928 fn bar(x: &u32) {}
 929         "#,
 930             expect![[r#"ty: u32, name: x"#]],
 931         );
 932     }
 933
 934     #[test]
 935     fn expected_type_struct_field_without_leading_char() {
 936         cov_mark::check!(expected_type_struct_field_without_leading_char);
 937         check_expected_type_and_name(
 938             r#"
 939 struct Foo { a: u32 }
 940 fn foo() {
 941     Foo { a: $0 };
 942 }
 943 "#,
 944             expect![[r#"ty: u32, name: a"#]],
 945         )
 946     }
 947
 948     #[test]
 949     fn expected_type_generic_struct_field() {
 950         check_expected_type_and_name(
 951             r#"
 952 struct Foo<T> { a: T }
 953 fn foo() -> Foo<u32> {
 954     Foo { a: $0 }
 955 }
 956 "#,
 957             expect![[r#"ty: u32, name: a"#]],
 958         )
 959     }
 960
 961     #[test]
 962     fn expected_type_struct_field_with_leading_char() {
 963         cov_mark::check!(expected_type_struct_field_with_leading_char);
 964         check_expected_type_and_name(
 965             r#"
 966 struct Foo { a: u32 }
 967 fn foo() {
 968     Foo { a: c$0 };
 969 }
 970 "#,
 971             expect![[r#"ty: u32, name: a"#]],
 972         );
 973     }
 974
 975     #[test]
 976     fn expected_type_match_arm_without_leading_char() {
 977         cov_mark::check!(expected_type_match_arm_without_leading_char);
 978         check_expected_type_and_name(
 979             r#"
 980 enum E { X }
 981 fn foo() {
 982    match E::X { $0 }
 983 }
 984 "#,
 985             expect![[r#"ty: E, name: ?"#]],
 986         );
 987     }
 988
 989     #[test]
 990     fn expected_type_match_arm_with_leading_char() {
 991         cov_mark::check!(expected_type_match_arm_with_leading_char);
 992         check_expected_type_and_name(
 993             r#"
 994 enum E { X }
 995 fn foo() {
 996    match E::X { c$0 }
 997 }
 998 "#,
 999             expect![[r#"ty: E, name: ?"#]],
1000         );
1001     }
1002
1003     #[test]
1004     fn expected_type_if_let_without_leading_char() {
1005         cov_mark::check!(expected_type_if_let_without_leading_char);
1006         check_expected_type_and_name(
1007             r#"
1008 enum Foo { Bar, Baz, Quux }
1009
1010 fn foo() {
1011     let f = Foo::Quux;
1012     if let $0 = f { }
1013 }
1014 "#,
1015             expect![[r#"ty: Foo, name: ?"#]],
1016         )
1017     }
1018
1019     #[test]
1020     fn expected_type_if_let_with_leading_char() {
1021         cov_mark::check!(expected_type_if_let_with_leading_char);
1022         check_expected_type_and_name(
1023             r#"
1024 enum Foo { Bar, Baz, Quux }
1025
1026 fn foo() {
1027     let f = Foo::Quux;
1028     if let c$0 = f { }
1029 }
1030 "#,
1031             expect![[r#"ty: Foo, name: ?"#]],
1032         )
1033     }
1034
1035     #[test]
1036     fn expected_type_fn_ret_without_leading_char() {
1037         cov_mark::check!(expected_type_fn_ret_without_leading_char);
1038         check_expected_type_and_name(
1039             r#"
1040 fn foo() -> u32 {
1041     $0
1042 }
1043 "#,
1044             expect![[r#"ty: u32, name: ?"#]],
1045         )
1046     }
1047
1048     #[test]
1049     fn expected_type_fn_ret_with_leading_char() {
1050         cov_mark::check!(expected_type_fn_ret_with_leading_char);
1051         check_expected_type_and_name(
1052             r#"
1053 fn foo() -> u32 {
1054     c$0
1055 }
1056 "#,
1057             expect![[r#"ty: u32, name: ?"#]],
1058         )
1059     }
1060
1061     #[test]
1062     fn expected_type_fn_ret_fn_ref_fully_typed() {
1063         check_expected_type_and_name(
1064             r#"
1065 fn foo() -> u32 {
1066     foo$0
1067 }
1068 "#,
1069             expect![[r#"ty: u32, name: ?"#]],
1070         )
1071     }
1072
1073     #[test]
1074     fn expected_type_closure_param_return() {
1075         // FIXME: make this work with `|| $0`
1076         check_expected_type_and_name(
1077             r#"
1078 //- minicore: fn
1079 fn foo() {
1080     bar(|| a$0);
1081 }
1082
1083 fn bar(f: impl FnOnce() -> u32) {}
1084 "#,
1085             expect![[r#"ty: u32, name: ?"#]],
1086         );
1087     }
1088
1089     #[test]
1090     fn expected_type_generic_function() {
1091         check_expected_type_and_name(
1092             r#"
1093 fn foo() {
1094     bar::<u32>($0);
1095 }
1096
1097 fn bar<T>(t: T) {}
1098 "#,
1099             expect![[r#"ty: u32, name: t"#]],
1100         );
1101     }
1102
1103     #[test]
1104     fn expected_type_generic_method() {
1105         check_expected_type_and_name(
1106             r#"
1107 fn foo() {
1108     S(1u32).bar($0);
1109 }
1110
1111 struct S<T>(T);
1112 impl<T> S<T> {
1113     fn bar(self, t: T) {}
1114 }
1115 "#,
1116             expect![[r#"ty: u32, name: t"#]],
1117         );
1118     }
1119
1120     #[test]
1121     fn expected_type_functional_update() {
1122         cov_mark::check!(expected_type_struct_func_update);
1123         check_expected_type_and_name(
1124             r#"
1125 struct Foo { field: u32 }
1126 fn foo() {
1127     Foo {
1128         ..$0
1129     }
1130 }
1131 "#,
1132             expect![[r#"ty: Foo, name: ?"#]],
1133         );
1134     }
1135 }